(a) Field of the Invention
The present invention relates to a battery module, and more particularly, to a rechargeable battery module having an improved cell barrier between unit cells.
(b) Description of the Related Art
A rechargeable battery module typically includes rechargeable batteries (also known as unit cells) connected in series.
The unit cells respectively include an electrode assembly, which is composed of positive and negative electrodes and a separator interposed therebetween, a case having a space for housing the electrode assembly, and a cap assembly combined with the case and sealing it.
The cap assembly may include positive and negative terminals disposed inside and outside of the case and electrically connected with the positive and negative electrodes. When the unit cell is prismatic, it forms a battery module by alternatingly arranging positive and negative terminals protruding from the top of the unit cell with those of another adjacent unit cell. A connector of a conductor is typically mounted by a nut to electrically connect positive and negative terminals having partially threaded circumferential surface. Unit cells are thereby electrically connected to each other to constitute a battery module.
Since the typical battery module includes several to tens of unit cells, it needs to effectively dissipate the heat generated from each unit cell. Particularly, when it is formed as a rechargeable battery with large capacity for a motor-driven device such as an electric cleaner, an electric scooter, or an automobile (for example, an electric vehicle or a hybrid electric automobile), the heat dissipation becomes very significant.
If a rechargeable battery module does not dissipate the heat well, it can be over-heated due to the heat generated from each unit cell and thereby cause misoperation of the device to which the rechargeable battery module is applied.
Since conventional battery modules have a cell barrier disposed between unit cells and tightly contact the surfaces of the unit cells and a coolant flows through the inside of the cell barrier to cool down the unit cells, heat transferring efficiency can be low.
In addition, when an external impact is applied to a device where the battery module is housed or the device is vibrated during operation, the unit cells or the cell barrier may move within the battery module. When the unit cells are moved, contact resistance is increased between a conductor which electrically connects the unit cells and electrode terminals. When the cell barrier is moved, the flow of the coolant is disturbed and thus the cooling performance may be deteriorated.
Further, when the cell barrier has a complicated shape, it becomes difficult to easily fabricate the battery module, which leads to expensive production costs. Therefore, the structure of the cell barrier needs to be simplified to reduce the production cost.